chore(package): update copy-webpack-plugin to version 5.1.0

Closes #66

Author: greenkeeper[bot]

package.json

@@ -58,7 +58,7 @@
     "babel-preset-env": "^1.3.2",
     "babel-preset-stage-2": "^6.22.0",
     "chalk": "^2.3.2",
-    "copy-webpack-plugin": "^4.5.2",
+    "copy-webpack-plugin": "^5.1.0",
     "coveralls": "^3.0.2",
     "css-loader": "^0.28.0",
     "element-ui": "^2.4.11",